Diketahui deret 3+6+12+...+192 a.tentukan banyak sukunya b.hitung jumlahnya!

a = 3
r = 6/3 = 2
Un = 3 x 2^n-1
192 = 64 x 3 = 3 x 2^n-1
2^6 = 2^n-1
n = 6+1 = 7
banyak suku = 7

b. S7 = 3 x (2^7 - 1)/(2-1)
= 3 x (128-1)
= 3 x 127
= 381